This invention relates to a power line communication system, and more particularly to a power line communication system utilizing a local area network to relay utility usage data to a transmitting meter for transmission to a central database.
A power line communication system typically transmits and receives data over standard electrical house type wiring. An example of such a system is the remote intercom system using electrical wiring within a building to communicate data between the transmitter and receiver. A system such as this does not communicate with an external database, nor does it communicate between two or more buildings.
Utility meter communication systems exist that communicate with a central database by way of a radio frequency transmitter. For example, U.S. Pat. No. 5,495,239 discloses a system in which utility meter electronics communicate with a remote interrogator in a vehicle as it approaches the utility meter in a building. Additionally, utility meter communication systems exist which are able to communicate via telephone with a central database as is disclosed, for example, in U.S. Pat. No. 4,833,618. Utility meters in these utility meter communication systems lack the ability to communicate with one another and consequently, each utility meter must communicate with the central database or mobile interrogator. It would be desirable for utility meters within a utility meter communication network to have the capability of communicating with one another between multiple buildings. Additionally, there exists a need for a power line utility meter communication system with the capability of communicating with other utility meters within a local area network and communicating with a central database.
Present utility meter communication devices employ several electronic parts which result in a high cost of acquisition and maintenance of the communication module. It is desirable to have a utility meter communications system with relatively few parts that communicates with other utility meters and that can be constructed cheaply, and that require little maintenance.
The present invention addresses the foregoing needs by providing a power line communications system that enables utility meters to communicate with one another over power lines utilizing a frequency shift keying communication technique to transmit and receive utility usage data from each utility meter so that at least one utility meter within a local area network necessarily communicates with a central database.
In an exemplary embodiment of the present invention a low cost power line communications system enables utility meters to communicate with one another over power lines utilizing a amplitude modulation communication technique to communicate utility usage data to each utility meter so that any one utility meter within a local area network indirectly communicates with a remote interrogator.
In a further exemplary embodiment of the present invention a narrow band bandpass filter circuit is employed which enables the power line communication system to select at least one very narrow frequency band within which to communicate utility meter data, thus avoiding noise and other communications pitfalls on the power line.